Carrier for stacked type semiconductor device and method of fabricating stacked type semiconductor devices

ABSTRACT

A carrier for a stacked-type semiconductor device includes an accommodating section for accommodating stacked semiconductor devices, guide portions guiding the stacked semiconductor devices, and grooves through which a fluid may flow to the accommodating section and to sides of the stacked semiconductor devices. These grooves facilitate the flow of gas or liquid on the sides of the accommodating sections, and it is thus expected that the flow of hot wind during the reflow process and cleaning liquid during the cleaning process can be facilitated. This improves the production yield and the cleaning effects. Holes for connecting the accommodating section to the outside may be provided at corners of the accommodating section. Gas may be guided from the lower side of the accommodating section, so that heat can be efficiently applied to the semiconductor devices and bonding failures therebetween can be reduced. Further, grooves connecting adjacent holes may be provided for accommodating sections adjacent to each other.

CROSS-REFERENCES TO RELATED APPLICATIONS

This is a divisional application of U.S. patent application Ser. No.11/341,984 filed Jan. 27, 2006, which is a continuation application ofInternational Application No. PCT/JP2005/001247 filed Jan. 28, 2005,which was not published in English under PCT Article 21(2).

BACKGROUND

1. Field of the Invention

The present invention relates to a carrier for semiconductor devices anda method of fabricating stacked-type semiconductor devices.

2. Description of the Related Art

Recently, portable electronic equipment such as mobile telephones andnon-volatile semiconductor memory media such as IC memory cards havebeen downsized, and there has been increasing demands for reducing thenumber of parts used in the equipment and media to downsize suchequipment and media. Thus, there has been considerable activity in thedevelopment of efficiently packaging semiconductor chips, essentialelements among the structural components used in the equipment andmemory media.

Examples of packages that meet the such demands are a chip scale package(CSP) having a package size substantially equal to that of thesemiconductor chip, a multi-chip package (MCP) wherein multiplesemiconductor chips are incorporated into a single package, and apackage-on-package (POP) in which multiple packages are stacked andcombined into a single-piece member.

FIGS. 1( a) and 1(b) show a conventional carrier for stacked-typesemiconductor devices (hereinafter simply referred to as a carrier).More specifically, FIG. 1( a) is a side view of a carrier 1, and FIG. 1(b) is a top view thereof. The carrier 1 is used in the process offabricating stacked-type semiconductor devices. The carrier 1 includesaccommodating sections 2 for accommodating semiconductor devices 4, andguides 3 for the semiconductor devices 4. The stacked-type semiconductordevices may be fabricated through a reflow process and a cleaningprocess. In the reflow process, hot wind is applied to the stacked-typesemiconductor devices 4, which are thus heated. The cleaning process mayuse a liquid for cleaning.

However, the conventional fabrication process for stacked-typesemiconductor devices uses solder for stacking the semiconductordevices, and hot wind is needed to melt the solder for bonding duringthe reflow process. It is also necessary to guide the sides of thestacked semiconductor devices so as to prevent the stacked semiconductordevices from deviating laterally. However, guiding all of the sides ofthe semiconductor devices may prevent the devices and bonding portionsthereof from having a sufficient temperature during reflow with hot windto adequately melt the solder, and a bonding failure may occur. There isanother disadvantage in the cleaning process. When cleaning the bondingportions of the stacked semiconductor devices that are put in liquid,the sides of the semiconductor devices that are all guided preventliquid from flowing efficiently and effectively, thereby degrading thecleaning effects.

SUMMARY OF THE INVENTION

The present invention has been made taking the above into consideration,and has an object of providing a carrier for stacked-type semiconductordevices and a method of fabricating stacked-type semiconductor devicesthat realize improved production yield and cleaning effects.

The above object of the present invention is achieved by a carrier for astacked-type semiconductor device comprising an accommodating sectionfor accommodating stacked semiconductor devices, guide portions guidingthe stacked semiconductor devices, and first grooves through which afluid may flow to the accommodating section from sides of the stackedsemiconductor devices. These grooves facilitate the flow of gas orliquid on the sides of the accommodating sections, so that the flow ofhot wind in the reflow process and the cleaning liquid in the cleaningprocess can be facilitated, thereby improving the production yield andthe cleaning effects.

The carrier may further include holes provided at corners of theaccommodating section. With this structure, gas may be guided from thelower side of the accommodating section, and heat may be efficientlyapplied to the semiconductor devices. This contributes to reducingbonding failures of bonding portions between the semiconductor devices.The carrier may further include second grooves connecting adjacent holesprovided in adjacent accommodating sections to each other. The carriermay also include third grooves connecting holes to outside the carrierthrough a side of the carrier. The carrier may further include holesthat are provided in the first grooves and connect the first grooves tooutside the carrier through a bottom of the carrier.

The first grooves may be provided along sides of the stackedsemiconductor devices, so that gas or liquid can be applied to all thesides of the semiconductor devices. The first and third grooves may bedeeper than a top of a lowermost one of the stacked semiconductordevices (where the top of the lowermost semiconductor device is coupledto another semiconductor device mounted thereon). This makes it possibleto broadly apply heat to the bonding portions between the semiconductordevices during reflow with hot wind and to facilitate the flow ofcleaning liquid during the cleaning step. It therefore improves both theproduction yield and the cleaning effects.

The first grooves may include a groove via through which a part of aterminal located at an end of the stacked semiconductor devices isexposed to outside the carrier. It is thus possible to broadly applyheat to the bonding portions of the semiconductor devices during reflowwith hot wind and to facilitate the flow of cleaning liquid during thecleaning step.

The first grooves may become wider towards the sides of the carrier.This further facilitates the flow of hot wind during the reflow processand cleaning liquid during the cleaning step, and reduces the volume ofthe carrier. The reduced volume of the carrier restrains the thermalcapacity thereof during the reflow process allowing the bonding portionsof the semiconductor devices to melt at a lower temperature.

The guide portions may be higher than an uppermost one of the stackedsemiconductor devices. With this arrangement, it is possible to preventthe occurrence of deviation in the stacked structure duringtransportation between the subsequent processes.

The guide portions may also be provided for at least two corners of thestacked semiconductor devices. Preferably, the accommodating section,the guide portions and the first grooves are portions of a single-piecemember.

The present invention additionally includes a method for forming astacked-type semiconductor device including the steps of stacking firstand second semiconductor devices in an accommodating section of acarrier having guide portions guiding the first and second semiconductordevices and bonding the first and second semiconductor devices by reflowin which a fluid is applied to the accommodating section from sides ofthe first and second semiconductor devices through grooves of thecarrier. The method may further include cleaning bonding portions of thefirst and second semiconductor devices through the grooves.

Thus, in accordance with the present invention, it is possible toprovide a carrier for stacked-type semiconductor device and a method offabricating stacked-type semiconductor devices capable of improving theproduction yield and cleaning effects.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1( a) and 1(b) show a conventional carrier for stacked-typesemiconductor devices;

FIGS. 2( a) and 2(b) show a carrier for stacked-type semiconductordevices in accordance with the present invention;

FIGS. 3( a) and 3(b) are cross-sectional views of the carrier inaccordance with the present invention;

FIG. 4( a) is a top view of the carrier in accordance with the presentinvention, FIG. 4( b) is a front view thereof, and FIG. 4( c) is anenlarged view of an essential part of the carrier;

FIGS. 5( a) and 5(b) show another structure of the carrier forstacked-type semiconductor devices in accordance with the presentinvention;

FIG. 6 is a top view of yet another carrier for stacked-typesemiconductor devices in accordance with the present invention;

FIG. 7 shows a further carrier for stacked-type semiconductor devices inaccordance with the present invention;

FIGS. 8( a) and 8(b) show a still further carrier for stacked-typesemiconductor devices in accordance with the present invention; and

FIG. 9 is a view of another carrier for stacked-type semiconductordevices in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will now be given, with reference to the accompanyingdrawings, of embodiments of the present invention. FIGS. 2( a) and 2(b)show a carrier for stacked-type semiconductor devices in accordance withan embodiment of the present invention. Referring to FIGS. 2( a) and2(b), a carrier 10 includes accommodating sections 11 for accommodatingmultiple semiconductor devices 4 to be stacked, guide portions 12 ₁-12 ₄for guiding the peripheries of the semiconductor devices 4, and grooves(first grooves) 13 ₁-13 ₄ for guiding fluid such as gas or liquid fromthe side surfaces of the carrier 10 to the accommodating sections 11.Arrows indicate the flows of hot wind in a reflow process and those ofcleaning liquid in a cleaning process. Preferably, the grooves 13 areprovided for all sides of the semiconductor devices 4. Although FIG. 2(b) shows only four accommodating sections, the carrier used in practicemay have a larger number of accommodating sections.

The grooves 13 ₁-13 ₄ are provided to facilitate the flow of gas orliquid on the sides of the accommodating sections 11, so that the flowof hot wind in the reflow process and the cleaning liquid in thecleaning process can be facilitated. This improves the production yieldand the cleaning effects. Further, the single carrier may be used forprocessing steps from the reflow process to the cleaning process. Thisreduces the number of parts and the cost.

The carrier 10 may be formed by cutting a metal plate, by casting or byforging, and is preferably a single-piece member. In InternationalApplications PCT/JP2004/012476 and PCT/JP2004/006265, which were filedin the name of the same applicant as of the present application, thecarriers are formed from separate parts. In contrast, in accordance withthe present invention, the carrier 10 is a single-piece member formed bycutting of a metal plate, by casting or by forging and has highprecision for processing. Further, the carrier 10 has high rigidity ascompared to the separate-parts structure and may be less damaged duringthe assembly process of the stacked semiconductor devices.

FIG. 3( a) is a cross-sectional view taken along a line A-A′ shown inFIG. 2( b), and FIG. 3( b) is an enlarged view of a part of the assemblyshown in FIG. 2( a). As shown in FIG. 3( a), a lowermost semiconductordevice 42 is placed in the accommodating section 11 of the carrier 10,and an uppermost semiconductor device 41 is then mounted on thelowermost semiconductor device 42. Connection terminals (solder balls)43 are provided to the lower surfaces of the semiconductor devices 41and 42. Electrode pads (not shown), which are connected to theconnection terminals 43, are provided on an upper surface of a substrateof the semiconductor device 42. The stacked-type semiconductor devicemay be fabricated by applying hot wind from the grooves 13 and anopening provided below the lowermost semiconductor device 42 duringreflow heating, thereby melting the connection terminals 43. Thesemiconductor device 41 may be a logic device, and the semiconductordevice 42 may be a memory device such as a flash memory. In this case,the stacked-type semiconductor device includes the logic device and thememory device stacked together.

As shown in FIG. 3( b), the grooves 13 are made deeper than the uppersurface B of the lowermost semiconductor device 42 (see a referencecharacter C). This structure makes it possible to broadly apply heat tothe bonding portions of the semiconductor devices 41 and 42 during thereflow process, and to broadly apply cleaning liquid thereto during thecleaning process. Thus, both the production yield and the cleaningeffects can be improved.

FIG. 4( a) is a top view of the carrier in accordance with an embodimentof the present invention, FIG. 4( b) is a front view thereof, and FIG.4( c) is an enlarged view of an essential part of the carrier. As shownin FIGS. 4( b) and 4(c), the grooves 13 are formed so that theconnection terminals (solder balls) 43 located at the ends of thesemiconductor device 4 can be partially viewed from sides P of thecarrier 10. The grooves 13 are formed so that the connection terminals43 located at the corners of the semiconductor device 4 can be partiallyviewed. This structure makes it possible to apply heat to the bondingportions located even at the ends of the semiconductor chips 41 and 42during the reflow process and to apply cleaning liquid thereto duringthe cleaning process. Thus, both the production yield and the cleaningeffects can be improved.

FIGS. 5( a) and 5(b) show another structure of the carrier for astacked-type semiconductor device in accordance with present invention.More specifically, FIG. 5( a) is a view that corresponds to a crosssection taken along a line B-B′ shown in FIG. 2( b), and FIG. 5( b) isan enlarged view of a part of the assembly shown in FIG. 5( a). As shownin FIG. 5( a), the stacked-type semiconductor device composed of thesemiconductor devices 41 and 42 are placed in the accommodating section11. In accordance with the present invention, the semiconductor devices41 and 42 are assembled within the carrier during the fabricationprocess for stacked-type semiconductor devices. Prior to the reflowprocess, the semiconductor devices 41 and 42 are merely stacked and arenot bonded. Thus, the semiconductor devices 41 and 42 may move inrelationship to each other after the stacking process and before thereflow process is finished. Thus, as shown in FIGS. 5( a) and 5(b), theguide portions 12 are formed so as to be higher than the uppermostsemiconductor device 41 (see reference characters D and E). With thisarrangement, it is possible to prevent the movement within the stackedstructure during transportation between the fabrication processes.

FIG. 6 is a top view of yet another carrier for stacked-typesemiconductor devices in accordance with the present invention.Referring to FIG. 6, a carrier 30 includes accommodating sections 11 foraccommodating multiple semiconductor devices 4 stacked together, guideportions 12 ₁-12 ₄ for guiding the peripheries of the semiconductordevices 4, grooves (first grooves) 13 ₁-13 ₄ for guiding fluid such asgas or liquid from the side surfaces of the carrier 30 to theaccommodating sections 11, through holes 14 ₁-14 ₄ provided at cornersof the accommodating sections 11, and grooves 15 ₁-15 ₄ for connectingthe through holes of the neighboring accommodating portions. The throughholes 14 penetrate the carrier 30 and reach the backside thereof.Although the through holes 14 shown in FIG. 6 have a circular shape, thethrough holes 14 may have any other shape, such as, for example, asquare shape.

The groove (second groove) 15 ₃ functions to guide gas to the throughholes 14 ₃, 14 ₅, 14 ₆ and 14 ₇ of the neighboring accommodatingsections, and the grooves (third grooves) 15 ₁, 15 ₂, and 15 ₄ connectthe through holes to the outside of the carrier 30. With this structure,it is possible to apply heat to the corners of the semiconductor devicesand to reduce bonding failures that occur at the corners of thesemiconductor devices during the reflow process with hot wind.

FIG. 7 shows yet a further carrier for stacked-type semiconductordevices in accordance with the present invention. As shown in FIG. 7, acarrier 40 includes an accommodating section 11 for accommodating astacked semiconductor device 4, guide portions 32, and 324 for guidingonly two corners among the four corners of the semiconductor device 4,grooves (first grooves) 33, and 334 for guiding fluid such as gas orliquid from the side surfaces of the carrier 40 to the accommodatingsection 11, through holes 34, and 344 provided at corners of theaccommodating section 11, and grooves 35, and 354 for connecting thethrough holes through holes 34, and 344 to the outside of the carrier40. In accordance with the present invention, the guides are provided toat least two corners among the four corners of the stacked semiconductordevice 4.

FIGS. 8( a) and 8(b) show a still further carrier for stacked-typesemiconductor devices in accordance with the present invention. Moreparticularly, FIG. 8( a) shows a carrier in which the grooves 13 areformed at an angle of ninety degrees with respect to the sides of thesemiconductor device 4. FIG. 8( b) shows another carrier having groovesformed at an angle of 45 degrees with respect to the sides of thesemiconductor device 4, in which a reference numeral 50 indicates acarrier, a reference numeral 502 indicates guides, and a referencenumeral 503 indicates grooves. As shown in FIG. 8( b), the grooves 503become wider towards the sides of the carrier 50 away from theaccommodating section 11. This shape of the grooves 503 facilitates theflow of hot wind during the reflow process and cleaning liquid duringthe cleaning step, and reduces the volume of the carrier 50. The reducedvolume of the carrier 50 reduces the thermal capacity thereof during thereflow process allowing the bonding portions of the semiconductordevices to be melted at a lower temperature.

FIG. 9 shows another carrier for stacked-type semiconductor device inaccordance with the present invention. Referring to FIG. 9, a carrier 60includes an accommodating section 11 for accommodating a stackedsemiconductor device 4, guide portions 12 ₁-12 ₄ for guiding theperipheries of the semiconductor device 4, grooves (first grooves) 13₁-13 ₄ for guiding fluid such as gas or liquid from the side surfaces ofthe carrier 60 to the accommodating section 11, and holes 61 ₁-61 ₄,which holes connect the grooves 13 ₁-13 ₄ to the lower surface of thecarrier 60. The holes 61 ₁-61 ₄ penetrate through the carrier 60 fromthe grooves 13 ₁-13 ₄. In practice, the carrier 60 has multipleaccommodating sections as described with reference to FIGS. 2( a) and2(b). The holes 61 ₁-61 ₄ respectively provided in the grooves 13 ₁-13 ₄facilitate the flow of gas or liquid, so that the flow of hot windduring the reflow process and the cleaning liquid during the cleaningprocess can be facilitated. This improves the production yield and thecleaning effects. Further, the same carrier can be used from the reflowprocess to the cleaning process. This reduces the number of parts neededfor manufacturing and the cost thereof.

Finally, a method of fabricating the stacked-type semiconductor devicewill be described with reference to FIGS. 2( a) through 3(b). Inaccordance with the present invention, a method of forming astacked-type semiconductor device includes the steps of stacking thefirst and second semiconductor devices 41 and 42 in the accommodatingsection 11 of the carrier 10 having guide portions 12 guiding the firstand second semiconductor devices, bonding the first and secondsemiconductor devices 41 and 42 by reflow during which a fluid isapplied to the accommodating section 11 and thence to the sides of thefirst and second semiconductor devices 41 and 42 through grooves 13 ofthe carrier, and cleaning bonding portions of the first and secondsemiconductor devices 41 and 42 through the grooves 13.

The preferred embodiments of the present inventions have been described.However, the present invention is not limited to the specificallydescribed embodiments, but may include various variations andmodifications within the scope of the claimed invention.

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 13. A method for assembling a stacked-typesemiconductor device comprising the steps of: stacking first and secondsemiconductor devices in an accommodating section of a carrier havingguide portions guiding the first and second semiconductor devices; andbonding the first and second semiconductor devices by reflow duringwhich a fluid is applied to the accommodating section and the sides ofthe first and second semiconductor devices through grooves of thecarrier, the grooves connecting with the accommodating section of thecarrier.
 14. The method as claimed in claim 13, further comprising thestep of cleaning bonding portions of the first and second semiconductordevices through the grooves.